Just finished dyno'g 2 RX-8's
 

Well I'm glad to hear the rating is down by Mazda because it wasn't pretty. On 91 octane, California gas.

http://www.xbmotoring.com/rx81.jpg

and

http://www.xbmotoring.com/rx82.jpg

Next time I'll try 100 octane.

That equals from 202 - 209 Crank HP assuming a 17% drivetrain loss. Using Mazda's figure of 238 HP that would be about a 27%-30% drivetrain loss. The difference between this and many of the others (done at 93 octane I think) is about 5- 10 WHP, which seems to make sense.

There is no way this engine is spitting 238 HP at the flywheel or that carbon fiber drivetrain was one big waste of money!! These numbers all seem to be consistent with my view that the RX8 felt about as fast, if not a bit slower than the RSX Type S and Celica GTS.

That's horrendous!
Can we assume that Mazda's 238bhp announcement is simply a diversionary tactic to stall the outcry and perhaps head it off. Perhaps the forum should put as much effort into pushing for an answer to the 'where is the stated 238bhp' question as it did for the 'where is the stated 247bhp' question. Something is VERY wrong here.

Granted I haven't been reading the other threads on this topic in depth and don't claim to be an auto mechanic in anyway, but according to these graphs and others I've seen....isn't it a bit suspicious that when the 3rd intake opens nothing much happens except that you lose power for a second? Their is no significant gain from only 2 inlet ports.

I would expect this graph to continue on upward to the annouced HP numbers (- drivetrain loss) from Mazda once that 3rd port opened....wasn't that the point of it? This falls right in line with what some people are experiencing with the lack of (expetected) punch above 6500rpm and/or the inability to rev easily past that point...this is clearly visible on this graph.

I guess the Renesis will not outdo the F20C in terms of linear torque curves? BTW..did the International Engine of the Year award only consider new engines because I can't see how they could have picked it over the F20C, given the Renesis's current performance.

Is that an AT or MT?

What's up guys. I'm actually a TSX owner and admin at acura-tsx.com and have been following the the RX8 and this interesting HP saga. I know a lot of you have very poor impressions of the TSX power plant and car in general. I'm not being a troll but wanted to post this tsx dyno as a comparison as I know a lot of you have very poor impressions of it.

http://photos.imageevent.com/provenc...31169_dyno.jpg


This is one of our users with the 6mt on a dyno jet, about 1500 miles on his car. Honda seemed to underate this motor, it's more like 205 hp or so and 180lbft.(we have another dyno showing 179hp but it's from a mag so I dont' know how believable it is)

It looks like another great Honda powerplant.

Looking the same........ how many miles on each car?

Honda seems to have made a bit of a compromise on performance with this engine. They gave it a lot of low end(relatively) at the expense of some top end hp. So far it seems to respond well to mods. Anyway like i said i don't want to hijack or be a troll. Just for comparison purposes. The car is heavier +fwd so it's not going to be as quick. We have one user all sock hit 15.5 @90.xxmph. (stock tsx tires are touring allseason)

Re: Just finished dyno'g 2 RX-8's
 

Actually, next time try 87 octane on one...

lower octane test
 

Trying a lower octane may help. It seems to give my car a couple extra horsepower and more importantly it seems to lessen the dips during the intake port switching. I posted some "dyno" tests here:
https://www.rx8club.com/series-i-tech-garage-22/more-g-tech-dyno-results-9402/

What was the temperature during the dyno runs? Even when I am running 93 octane, my car seems to dislike the heat. On a very hot day my car will lose over 10WHP due to the weather. I imagine it would be even worse on a dyno without air circulation of the car in motion. I'm waiting for a nice 50 degree night to do a cold weather test.

thanks Dan as i was questioning the same thing. The One RX-8, what exactly makes you think 100 octane would help here? you dont seem to understand the differences between octanes.

How eactly does octane work with rotary motors?

It's a trueism that lower octane fuel is less refined and thus has more potential power in it. With a piston motor what higher octane does is require a highe rcompression to be ignited. this lets you adjust ignition timing for more gain, but not because the fuel itself has more energy in it.

Both cars had around 1500 miles. Both were 6MT's.

No temp data while on the dyno. I know while driving underhood temps have reached the 170F near the the throttle body. Where the air is drawn from however is close to ambient, right under 90 degrees. I couldn't get the IAT's due to the CAN system that Mazda/Ford uses.

I will try 87 octane as well.

I am testing on claims only. 95 is the recommended octane. 100 octane is my next closest choice.

Re: lower octane test
 

Outside temps are noted on the dynograph. The first car was run in the afternoon and the other at 8 am. These cars seem to have one of the most heat generating engine bays that I've worked with.

Re: Re: Just finished dyno'g 2 RX-8's
 

Do you think we should be using 87 octane. This is my first rotary and I have been using the Premium. 15-19 mpg. Thanks

I noticed that the charts seemed a little wavy after the 7200 rpm dip. This may have been the ECU backing off the timing due to detonation in the heat. I'm just taking a guess but it would explain the low numbers in the heat. I'm going to try my car on some 87 octane in the 85 degree heat in about an hour today. We'll see what it does.

if you are getting detonation isn't higher octane the way to go? Or is that a difference in piston vs. rotary. Intuitively does't seem so as higher octane requires higher heat/pressure to combust.

Damn those numbers are low.. My Prelude dyno'ed around 168whp with a few basic mods.. :(

At around 7400rpms the hp/tq take a big dip and never seem to recover after that. :(

Exactly my thought!, A Car Mag complained that the third stage intake ports are stuck and thus there was a loss of power. Mazda found out that this is the case, and instead of recalling all engines, it just gave out rebate/buy back deals... That totally sucks!!

I would expect the Torque curve to stay above 125 lbft all the way to redline. It seem that the 3rd stage is not working.

We saw a drop of 25 WHP on the Acura CL-S when the 2nd stage intake valave was faulty !!

Nashua.

it was SCC on a pre-production car before any production cars even in japan were on the road. the stuck port was found to be a manufacturing problem from the parts supplier and was fixed before production. there have been no reports of any stuck tertiary ports in any production car in Japan or the US.

After all the HP saga, all the guessing and speculation. Mazda's admittance of lower than stated power, etc, etc. I dynoed my car at 1050 miles 5 weeks ago and averaged 180whp... bla, bla, bla..

Today, I got spanked [actually about even] by a Toyota Solara V6 AT. It's 225hp and 3241lbs. Without any technical explainations - the RX-8 should NOT trail behind a Solara!!!! It's 13hp less and 241lbs heavier with an auto tranny.

Yes, the RX-8 is fun but it's NOT fast. Zippy. Weee. Where is the Zoom Zoom?

Mazda is LYING about the 9hp. It's WAY more than that. A $21,000 family car can pull on my $30+k "sporty" car.

FYI: Mine is a 6MT with 2700 miles, only me in the car and a half tank of gas.

That sucks big time. I just came from short test drive of the RX-8 6-speed. At 180 WHP SAE that is some 210 HP at the crank give or take couple HPs. That is a loss of 40 HP from that 247-250 HP claim. Mazda should Supercharged all RX-8 to get to 250 HP or 210 WHP! That is a 25 lbft at the wheels and 30 WHP lost...!!

My CLS will do 14.6s in the 1/4 in the 90F 85%Humidity summer heat. My CLS is so heavy like... at 3495 with me at 185lbs. I dynoed at 238 WHP Acutual and 226 SAE WHP.

I believe if the RX can lay down 135 lbft and 210 WHP at 8500 rpms it should hit low 14s and hi 13s...

Ah... Mazda is scewing us all.

Nashua.

.

how old was the grandmother driving the solara and what was the total weight with her, the car, the quarter tank of gas, the load of groceries in the trunk and thespare tire she was toting?
also did you have your radio and auto dimming mirror on? i hear having them off you can shave off about 2 hundredths of a second in the 1/4 mile if you turn them off.

also the peddle on the left is the clutch which if depressed allows you to move that stick on the console to your right to a different gear selection, then you have to release that clutch peddle again and depress the accelerator peddle which is the one to your right. also the larger stick thing that pokes up to the right of the previosly mentioned gear selector stick is the hand brake. press the little button on the end and let the stick go all the way to it's lowest position.

I mentioned in another thread that there is no way it is putting out 238hp and no way it'll do 0-60 in 5.9 sec. Well not the ones being sold to the public anyway. I based this on the fact that the motor is behaving just like any large streetport rotary putting out about 200hp at the crank with a RB holley or weber. I am dismayed at the fact that with all the hype and cutting edge technology they came up with the same numbers as you would get with a streetport 13B of the eighties with a carb on it! Don't be surprised if some of you satisfied owners get smoked by a $2500 84-85 RX-7 since the 8 is oh about 600-700 lb heavier.
I know, I know, it is the overall value that counts and the styling and handling etc. that a lot of you don't mind paying the $32k for. But let's face it, almost all rotary enthusiasts were looking forward to a 250 N/A rotary. Any input on the j-spec engines? I would be really surprised if they had the extra 30-40hp.

TurboSE, did you just compare a stock vehicle to a modded vehicle? how about your modded vehicle to a similarly modded rx-7 twin turbo?

Are we saying that the RX8 makes the same power but less torque than a TSX? Doesn't the TSX have the same engine as the RSX-S? Don't both TSX and RSX-S sell for thousands less than a comparable equipped RX-8? Mazda better get their acts together, it's a competitive market, and consumers are not dumb.

define "we" maniacman.

You know what I think. Instead of going ON AND ON AND ON about speculations of what could be the problem. I say somebody tries to figure out what it is. If the only difference between the US version and the Japanese one is the stuff they put on for emissions then why doesnt somebody figure out what that stuff is and take it off. Without all the stuff added on for the US model for it to pass emissions it SHOULD dyno the same as the Japanese version. If it doesnt then thats not the problem. I dont know what this involves but if its just stuff thats bolted on then it should be pretty easy to figure out. If its electrical and has to do with computer stuff then could we possibly get the Japanese electrical stuff and install it in the US version. Im sorry i dont know what any of this is called but i know a little, and it seems that this shouldnt be too hard to figure out. There has to be somebody we can turn to besides Mazda to find out whats wrong because they obviously dont want to help. If we can find out whats wrong with these cars then we can get on Mazda's case and know exactly whats wrong with the car and demand that they fix it. ....and that would be super!!:D

well, my point was that 20 years later you would expect a more dramatic improvement than what you would get by porting any old 13B and a few bolt-on upgrades. All the hype about how much more efficient the side port configuration is got me excited about the future. Now I cannot find one person who even gets 25mpg so there is not much improvement in power or economy in my humble opinion. Yes it is the most powerful n/a rotary but it cannot even outperform a 4cyl honda powerplant.:(
Btw, if my car had a similar sized turbo as the 3rd gen rx-7, I would have very similar straightline performance since the motor internals are nearly the same. What it boils down to is that the displacement is the limiting factor for the 13b configuration. I think the rx-8 and renesis would be an attractive buy if it was priced at $22-24K max. Afterall, what made the rotary rx-7 attractive at first was CHEAP performance. What killed it was the eventual hefty price tag.

We have Paul Yaw who is quite a 1st gen guru who has a renesis on his engine dyno. I haven't seen him post of late since mazda's downward revision. Maybe he is a little dissappointed as well???

It's looken like the rx8 is a pile of trash after all.......overrated on the fuel economy, overrated on the HP....and yes, i'm an FD owner. I hope Mazda gets their shit together soon.

Gee, thanks for that very constructive post!

why thank you...you all know it's true. I'd expect an rx8 to beat a fucken toyota solara in a straight line at least even with the 13 MPG. HAHAHAHAH

More detail... The driver was an ~18yr old male [mom's car] we were at a stop sign. My lane in about 1/8mi closed into his. I didn't expect him to mess with me but I had a lot of motivation to get far enough ahead to move into his lane after an 1/8 mile. Easy off the line for me - he jumps on the Solara. FULL throttle, I shift at about 8.5k or so [again, easy] fully expecting that I would easily pull ahead without a full-on nano-second powershift. At this point he was about 2ft ahead and I was BARELEY pulling on him. The 1/8 mile was very quickly coming to an end and he let up first and I coasted in front. There is no way, even with an 8,000 pm drag start and a perfect 1-2 shift that I could have pulled by if he did not ease up. WTF.

I never purchased the car [first in Houston] to drag race. I do, however, feel ripped-off. Not that the car is 9hp shy according to Mazda. If it was ONLY that much I would really care. 30+ hp has my blood BOILING fueled my MAZDA LYING. If the flywheel produced 238hp and the car is 3000lb, it would be a different experience. If Mazda said from the beginning that it would be 210hp I would still buy it. Now, I feel like a sucker. I don't want to give it back - I want an RX-8 with at least 238hp of not 247.

BTW - I have been an EXTREME rotary fan since 1985 and a continuous owner for more than 13 years. I have built a number of rotary engines an enjoyed every moment of it. I have enjoyed most every moment of the RX-8.

Bad RX-8 Moments:

1) When I dynoed the car 5 weeks ago and first discovered it's little secret.

2) When I realized I have no chance of passing a Toyota Solara if he/she decides to accelerate.

3) When Mazda is F^+$(ing lying about a 9hp correction that does not affect performance.

4) When I realized that the RX-8 will be laughed at by other enthusiasts unless I drop $$$$ on mods so that I can hang with Boxters, and S2000's.

I am at a loss. I waited many years to own a fresh, brand new, rotary car. Huge improvements from previous NA rotarys, but not keeping up with the 280+hp [real hp] V6's.

Mazda is paying him to keep quiet.


I hope this may provoke a response from one of the few people who can shed light on this. ACOSTA RACING has pulled a RENESIS for the 20B transplant. I would pitch in $$ to put that on a dyno.

Hi Skyline,
They both ar I-VTEC engines, but the TSX uses a 2.4 liter 4 cylinder while RSX-S uses a 2.0 liter. They are both rated at 200 HP at the crank, but the TSX has a lower redline and more torque due mostly to its greater displacement. The RSX-S has an excellent torque curve, in fact its very similar in shape to the original one for the RX8 albeit at lower amounts. That's one of the reasons I thought the RX8 was short on power at the top end because it felt very different as compared to the RSX-S (the RSX-S's torque curve increases slightly and stays flat until its HP peak where the RX8's torque curve drops after 6,250 RPMS).

BTW...the RSX-S does this pretty clean. It does very well on all pollution tests (including Greenhouse Gases) and averages about 28 MPG.

A lot of people thought Mazda (with the Renesis) would seriously challenge Honda as the king of the small engine. However, it looks like those thoughts were a bit too premature.

Hmm....new dynos, consistent results. This trend is starting to look disturbing.

BTW, was the question of "is this done on a MT" been covered?

EDIT: oh ok I saw it, nevermind.

If i am reading these dyno plots right , and my understamding is that the first two ports on th low and high power versions are the same, we could expect the 4-port engine to put out about 169 whp with the manual transmission and CF driveshaft (13% loss:) ) so maybe with the AT and regular drive shaft we could hope for 162whp or 17% drivetrain loss.

those more knowledgable please expose any inaccuracies in this as the only dyno graphs I have ever seen are on this forum--but I can tell when the third port opens @ 7250 by the canyon in hte graph:mad:

I dont understand why you want to engine dyno the RX-8. Its not like this is a different engine then the one in Japan. The one in Japan is putting out the correct amount of HP so we know its not the engine. Just saw a clip of an RX-8 going 160mph. The engine is very powerful but something about what they have done to pass emissions in the US has totally restricted the engine somehow. Find out what that is and this whole issue will be solved. I agree with 1stRX8 on mazda keeping this guy quiet, and i wouldnt rely on him for an answer. Figure out what they did to the US version and remove it then dyno it and you should see your missing HP.

Wanted: Japanese dynos
 

Exactly! I would be very interested in seeing some dynos from a Japanese spec high powered model.

Think about it for a second.
When Mazda had the cars out for the magazine guys to test they were getting awful performance.
Then they pulled the cars and came up with that excuse.
There is nothing to show they were being truthful

It seems much more likely that the performance was sucking, and this was just another lie they told to try and hide the real power levels.

i thought someone dynoed a japanese version?

ill search the boards to makesure im not mistaken, if indeed i do find something, ill link it in
________
Body Science

Partovi....
I have no doubts about the engine. I am more interested in the ECU and other support components that are different on the US model. I really would like to know if my [and others] gueswork math is close to reality. I figure my car is making in the neigborhood of 217hp... 21 shy of the 238 and 30 shy of the 247 expected. This based on WHP measurements of ~180.

Measuring a full US spec SYSTEM would give us an idea of how bad Mazda is doing on this sensitive topic. They have A LOT to lose and will protect their interests - It's Business. I someone has the capacity to call the bluff - we would all likely end up with 21 more hp in our cars or at least more money.

On the other hand -

Good RX-8 Moments:

1) While on the return leg of our California road trip, we're followed up a mountain pass by an Acura TSX. I thought "how cute, he wants to play" (Our RX-8 had 2 adults and 2 wks worth of luggage on board, the TSX driver was solo). I pick up the pace, and as I accelerate through the second curve I see the TSX understeering into the wide shoulder lane. Talk about lame - that thing couldn't even keep up with the loaded down RX-8 being driven at about 7/10ths (no tire squeal on the curves from me). He kept trying, but quickly disappeared from view completely.

Who cares if other cars have similar power, when they handle like pigs? FWD sucks, a properly done RWD chassis rules in the turns. The RX-8 is a balanced package. Go ahead and return your car and buy a RSX-S or whatever, and continue with your stoplight drag races. You're missing out on the best capabilities of the RX-8.

Not to say that I'm pleased that Mazda wasn't especially careful to avoid the same mistake again (and to suggest that they deliberately mislead RX-8 buyers is ridiculous), but I'm interested in what was changed and when someone will be able to develop a new ECU program to reflash our existing ECUs. It looks obvious from the dyno plots that the third ports are where the problem is... (along with the third intake tract, etc.)

Regards,
Gordon

Just an observation on those dyno plots (but I am by no means an expert, so please tell me if I'm wrong) but they appear to have been done in 3rd gear.

I thought for the most accurate readings a dyno pull was done in whichever gear ratio is closest to 1.0:1.0. Is this not the case?

I know 5th gear seems awfully high for a dyno pull, but well, that is 1 to 1.

Agreed.

I did not buy the 8 on HP/weight ratio alone. I like the car very much. My wife and two kids can come along for a very fun ride. I don't mean to bash the 8, but rather Mazda for not FULLY owning up to a glaring flaw in the car. I am sure they could deliver 250hp if they had no concern for emissions. However, emmissions laws aren't new. How could a team of very high-end engineers miss that? I don't think they did. The only way this type of issue "slips" is via upper management avoiding initial PR slams the the RX-8 is underpowered. I would venture to say that HP ratings are very important to sporty drivers - [regardless of the weight of the car, ironically].

If the general public saw a commercial for "The All-New 210hp RX-8 for ONLY $30k", I think it would create a significantly different response than "The All-New 250hp RX-8 for ONLY $30k". I don't think that Mazda did this on purpose. I do think that the Marketing dept. put unreasonable pressure on engineering to get the HP number to a marketable level. The RX-01 was doing 270+hp, but had no concerns about emissions at the time. Marketing did some quick-calcs and decided that 250 was the right idea - the published "target hp" was 250.

My biggest rub with Mazda remains: It's A LOT more than 9hp-Admit it!!! And fix it. I don't care about $500 and maintenence. I don't want to give the car back. 238hp would be fine - 217 is NOT fine and that is what my car is developing.

Has anyone considered trying to purchase a JDM ECU for their car?

SC